using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

class Magatro
{
    static void Main()
    {
       int cnt = 0;
       for(int i = 0; i < 1000; i++)
        {
            int[] NK = Console.ReadLine().Split(' ').Select(s => int.Parse(s)).ToArray();
            cnt += (NK[0] - 1) % (NK[1] + 1) == 0 ? 1 : 0;   
        }
        Console.WriteLine(cnt);
    }
}